This evening I had the #2 spark plug blow off the head. I will be calling Autohaus in the morning, but I expect to hear a lot of laughter on the other end when I inquire about a warranty replacement. Has anyone in the St Louis area had this experience? I know Ron Flier has been bitten by it. Has anyone else had this happen? How have you fixed it?

 

Dang! No, I haven't heard about this being an issue. How was Ron "fixed"? What are your thoughts on the cause?

 

This is a very common problem with MINI's. There are several long threads on the board. Basically it is almost always #2 and it is due to the plugs backing off. BMW/MINI hides behind someone "unqualified" changing spark plugs instead of their mechanics or modifications, like SC underdrive pulleys or even the Iridium spark plugs, voiding any claim against them.

Ron ended up replacing the head. Some helicoil or put an insert in, but I would think even that requires head removal. I talked to him just yesterday about this. he said he went with a ported & polished head but it ate away some of his low end power and torque from other mods.

As I said, I don't expect MINI to step up to the plate. Personally I think this one is ripe for a class action lawsuit and I just may look into that option if I don't get some satisfaction from MINI. I mean I only have 35K miles and I'm just out of the 4 year warranty. Spark plugs shouldn't back out and if the engine is supercharged from the factory it should have soem design margin to take some additional boost from u/d pulleys. I bet an automotive expert could determine how much extra pressure is placed on the engine and determine if mods would have impact on the failure mode (plugs unthreading themselves).

Peter R

 

Are you running stock plugs?

 

We actually ended up fixing Ron's car. It runs a little better now.

If I can help let me know.

 

I bought the car used, but to answer your queston, no they aren'tthe stock plugs. I have heard that has been a cause for claim denial as well. That is such a poor cop out since this happens regardless of the brand of plug.

 

I actually spoke with Ron this morning and he mentioned you. I presume you must be Leyland. Ron said you ended up swapping in a new performance head for him. He is in the process of detuning the MCS and may want to repair the old head.

Ron is out of town and I am about to leave myself. Ironically we're driving through Indy and if I didn't have another 800 miles to go from there to my destination I would stop in to see you. Ron and I left off that we would regroup after the holidays.

Do you helicoil the head or do you use an insert? Would you recommend doing all 4 while the head is in your hands? Once I fix this I don't ever want to deal with it again.

 

I only ask because i've only read about this happening with non-stock plugs, correct me if i'm wrong. I've had absolutely zero problems with the plugs i'm running. They are the same ones they put in the JCW cars, and they are expensive, but cheaper than removing the head to repair.

 

A helicoil and an insert are the same things, just different names. Helicoils work great for spark plugs in aluminium heads (after all, they are english heads ). I have done several in different applications over the years. If you are taking the head off to do it then I would certainly recommend doing all of them while you are there already. Cheap insurance. They actually end up stronger than the original thread.

Again, proper torque is mandatory for every fastner. With a Helicoil you will also not have to worry about steel vs aluminium when removing the plugs in the future. Heat transfer away from the plug to the head should be almost as good as without the Helicoil.

 

That's my thinking as well.
How about the thought of also taking advantage of the head being out to port match and polish the head? Anyone have experience doing this?

 

I've heard it happenign with all forms of plugs. Brand is not the issue. It is my understanding that up to some production number all heads were not properly machined (hence always the same plug thread fails) and the plugs back out and eventually are loose enough that cylinder pressure overcomes thread strength and the plug is ejected. Clearly a manufacturing or design issue. The short term preventive solution I've seen distributed in all forum threads is constant checking of plug torque. My car is a 2002 and I failed to do this. I only bought it three months and about 3000 miles ago. I don't know if the JCW plugs are any better as much as I think they are on newer production heads with proper machining.

 

That seems to be the key. And shouldn't be "our" problem if something happens. Especially since there is so much talk about the problem.

It's not un-heard of for certain plugs to be more susceptible for failure. Temps can increase internally due to water passages, varied wall thicknesses, relayed heat from other internals, airflow around the cylinderhead/plug in question, etc. I have experienced this issue several times on Porsches, VW's and Jaguars.

The problem, however, has ALWAYS been a design flaw or engineering limitation with that particular motor. NOT the fault of the car owner.

Keep us in tune with what transpires.

 

I have 2002 Cooper S, about 6 months out of warranty, 35k miles. Last night it ejected the #2 spark plug. As has been reported on this thread and elsewhere this is a very common failure among MINI's. That I know of MINI (BMW) has not paid for any repairs to anyone claiming that modifications, including doing your own spark plug replacements are the cause of the problem.
My question is if anyone knows of any class action law suits in this regard. I'm not the suing kind, but I expect that I won't get any satisfaction from MINI and am looking at my options beyond the immediate need for a repair.
Can anyone recommend a way to find out if there is a class action underway?
If there isn't, is there anyone out there that wants to start one?

 

Did you have stock plugs installed at the time?

 

https://www.northamericanmotoring.co...ad.php?t=87433

 

Threads Merged with redirect left in the St. Louis forum to this thread.

PARTSMAN: you're experience matches my own. The *only* time I have seen this problem is with non-stock plugs.


Prima: There is no defect in the way the stock head works with the stock plugs. There are problems with aftermarket plugs being installed and those problems are compounded when the owners of non-stock plugs do not check the torque of the plugs regularly.

Caveat Emptor

 

I purposely click on the blown plug threads just to see what plugs were being used.
Like I stated earlier in this thread, I have the JCW plugs installed(NGK # is in my sig) and have had no problems. I did check the torque on them a couple times, and they have been perfect.

 

I've got the same fascination.
Checking the torque seems to be the real key.

Me, I know I won't keep up on checking the torque regularly, so I don't bother with the plugs (plus I have a MC now, so you know ).

 

Interesting? or Weird?
Makes sense to me.
I hear what you're saying, it's also one less thing to worry about.

 

Me and buddies, one of which is a mechanic, have sometimes installed Helicoils with the head in-place. Place a 2 to 4 sq. in. piece of woman's nylon hose into the cylinder head to catch metal flakes. Put a lot of grease on the tap (that will cut the Helicoil threads) to catch metal flakes. Remove grease and nylon after cutting Helicoil threads. Then install Helicoil insert with some lock tight. What few little aluminum flakes that are not recovered do not cause harm.

Other notes: had a racing motorcycle with aluminum head that expanded much faster than spark plugs. To keep plugs in, we applied one small dallop of Yamabond, Three Bond, or similar material. These are grey gasket materials that never harden. It is used when putting 2-cycle engine crank cases together. You don't need much on each plug. It is a very cheap insurance.

 

Like others here I have been tinkering with cars and engines for a long time including teaching high school automechanics for a good stint.

I installed Iridiums along with a set of Kinsborne wires on Artoo (2003 Cooper S) at 35,000 miles after the maintenance warranty ran out. There was little noticeable difference other than piece of mind. I also change the oil every 5,000 and since this has been an issue use that time to check the torque on the plugs. Each time they have been perfect, 4 times now.

My question is. On the engines that have ejected #2 or any other plug were they 1-Installed with a little drop of antiseize or a big glob figuring more is better? And 2-Were they torqued in to the requisite 20 ft/lbs with a good quality click-type torque wrench (perferably 3/8 and not the one they torque their wheels with) when they were put in rather than using the old, crush the washer and then a quarter turn old timer (that's me but I do keep learning) method? BTW. I learned to torque plugs when Chevy made aluminum heads available in the 60s and I was lucky enough to get a set for my small block and have been doing it ever since.

Following this thread for a long time it seems to me that if there were a flaw in the head, stock plugs originally installed would be ejecting as well and I don't see that. Only aftermarket ones installed later. Since the body of the plugs are similar (steel with a crush washer) my thoughts take me to the installation process which may be a little more critical than people expect. Also, I don't remember seeing any threads (I may be wrong) where the dealer installed plugs (I assume they torque them) and they were ejected. JCW, stock or any other plug included.

As for direct experience I have posted that a friend's friend came to me with this problem and although we were prepared to take the head off and install a helicoil we did fix it with a BackTap and it seems to be holding fine. He replaced his wires and plugs and did not torque them and even did it when the engine was warm after he drove back fromt he parts place. I suspect he overtightened his plug but there is no way to tell now.

So, what are the other experiences? I'd say class action on window motors and PS pumps and fans but I am not inclined to say that here. At least not yet? What's the collective wisdom?

Rich

 

Gary Stuckle's Back-Tap is indeed an amazing invention. And the OEM plugs are NGK so I'd expect no problems with aftermarket NGKs either, assuming they are properly installed.

Plugs back out all the time due to improper installation in all makes and models; it's just that with aluminum threads all that hammering (from the steel plug bouncing up and down with combustion) and the red hot gas leaking probably combine to rapidly fatigue the aluminum and cause it to fail.

The threads on the plugs are no longer or shorter than others used for decades with a very standard 3/4" reach and 14mm diameter. I doubt the aluminum alloy used in the head is any different than in many other engines, or the threads are miscut. If anything, it could be the water jacket may just be a bit too close to #2 seat, allowing it to flex a little and a less than perfectly tightened plug gasket to loosen.

Something to consider is you'd probably hear the ticking in a Corolla soon enough to go fix it, but if you've modified your MCS to be LOUD (and it is already noisy in stock form) then you may miss the warning.

 

Thank you. Thank You for this thread. I replaced my plugs for last summer's auto cross season. When I installed them, I torqued the after market NGK plugs to 20 ft lbs. 2500 miles later, I'm reading this discussion, and decided to go check the plug tightness. ALL were loose by about a 1/8 of a turn!! Those little buggers do back out! Thanks for the heads up. (JD)

 

There were issues with the aluminum used in the earlier heads. Randy Webb pointed this out. It is an undisclosed problem that mini had with earlier head castings.
The problem has been resolved for some time. It seems the early minis are the ones with these problems.

 

Twice for me. Both times #2 loose. The fact that #2 is always the culprit for everyone discredits any notion its an installation error. '03 S nonstock plugs in all 4 holes.